Norme Tecniche – UNI

In Italy the organization qualified for operating in the chemical sector of paints for décor is UNI (BSI in the United Kingdom, DIN in Germany and AFNOR in France).

The UNI rules useful to understand the technical characteristics of the Chrèon products for internal use are:

UNI 13300 Water paints for internal walls and ceilings. Classification
It specifies the most significative characteristics for the painting of internal walls. It begins with the description of the end use and of the nature of the resin. Then the brightness and granulomery are specified. As functional characteristics it indicates the moist brushing (also called “resistance to wash” or “washability”) and the covering power, considered as contrast.

UNI 10795 Emulsion paints for internal parts – important characyeristics for comparative and tests non-comparative
This rule has been prepared in order to add others or different criteria to those ones prescribed by EN 13300. By indicating the important characteristics, you can quote the necessary criteria for a complete classification of emulsion paints for internal parts, considering also the resistance to wash and the covering power

These are the UNI rules which are helpful for a better comprehension of the technical characteristics of Chrèon products for external parts:

UNI EN 1062-3 Determination and classification of water transmission (permeability)
Given that the ideal paint should have a high permeability to steam and a low permeability to water, the most important is the second one: the damages that water can create if it penetrates through the wall or through the concrete are famous. A paint with a low permeability can reduce this damage. The permeability to steam is very important when in the wall there is some water, either in form of building water, or as humidity, or also as infiltration that can’t be eliminated. The permeability to steam from the internal to the external parts depends also on the permeability of the wall: concrete, bricks, isolating layers, previous painting coats. The permeability to steam is important especially when the walls have a limited thick.

UNI EN 1062-6 Determination of the permeability to carbonic anhydrid
This characteristics is important for paints to be applied on cement/concrete. The cement is highly alkaline, and this characteristic prevents the iron rod from corrosion, as it has a passive action on it. But the alkaline substances tends to absorb the carbonic anhydrid of the air, which neutralizes the alcalinicity. So the corrosion of the iron rod becomes possible, with rust, increase of volume, crackings, detachment from the iron. Extreme case: weakening of the structure.